1. Field of the Invention
The present invention is directed to a power converter and more particularly, to a timing generator and a timing signal generation method for a power converter.
2. Description of Related Art
A DC-DC power supply design nowadays usually adopts a constant on time (COT) architecture. FIG. 1 is a schematic diagram illustrating a power converter 100 based on the COT architecture in the related art. A comparator 110 generates a compared signal CM by comparing an error signal Err with a ramp signal RAMP. A magnitude of the error signal Err is related to both a feedback signal Vfb and a reference voltage Vref. A timing control circuit 120 provides a pulse width modulation signal PWM according a constant on time mechanism and the compared signal CM, in which a width of an On-time Ton is related to an input voltage Vin and an output voltage Vout.
FIG. 2 is a schematic diagram illustrating the waveforms generated in the power converter 100. Referring to FIG. 1 with FIG. 2, the pulse width modulation signal PWM is decided by the error signal Err and the ramp signal RAMP. Meanwhile, when the compared signal CM triggers the timing control circuit 120, the timing control circuit 120 starts to count a fixed On-time Ton of each period in the pulse width modulation signal PWM. However, despite that a conventional pulse width modulation operation architecture may achieve a fixed frequency effect, when the output voltage Vout is changed with variation of a load current Iload, the timing control circuit 120 is still providing the same energy with the fixed frequency within one period, which results in that a power converter 100 to exhibit a poor performance during a load transient period.